Transmission of wide bandwidth signals in a network having legacy devices

ABSTRACT

A method for generating a preamble of a frame for a wide-bandwidth channel wireless communication begins by generating a legacy carrier detect field. The method continues by generating a channel sounding field, wherein the channel sounding field includes a plurality of tones within the wide-bandwidth channel, wherein a first set of the plurality of tones corresponds to tones of a legacy channel sounding field. The method continues by generating a legacy signal field, wherein, in time, the legacy signal field follows the channel sounding field, which follows the legacy carrier detect field.

This patent application is claiming priority under 35 USC §120 as acontinuation patent application of co-pending patent applicationentitled TRANSMISSION OF WIDE BANDWIDTH SIGNALS IN A NETWORK HAVINGLEGACY DEVICES, having a filing date of Jul. 10, 2007, and a Ser. No.11/825,868, which is hereby incorporated herein by reference in itsentirety and made part of the present U.S. Utility Patent Applicationfor all purposes.

U.S. Utility patent application Ser. No. 11/825,868 claims priorityunder 35 USC §121 as a divisional patent application of patentapplication entitled TRANSMISSION OF WIDE BANDWIDTH SIGNALS IN A NETWORKHAVING LEGACY DEVICES, having a filing date of Oct. 26, 2004, and a Ser.No. 10/973,612, now U.S. Pat. No. 7,400,612, which claims priority tothe following:

-   -   claims priority under 35 U.S.C. §119(e) to the following U.S.        Provisional Patent Applications: U.S. Provisional Application        Ser. No. 60/544,605, entitled “Multiple Protocol Wireless        Communications in a WLAN,” filed Feb. 13, 2004; U.S. Provisional        Application Ser. No. 60/546,622, entitled “Wireless        Communication Between Stations of Differing Protocols,” filed        Feb. 20, 2004; and U.S. Provisional Application Ser. No.        60/575,954, entitled “Transmission of Wide Bandwidth Signals in        a Network Having Legacy Devices,” filed Jun. 1, 2004; and    -   claims priority pursuant to 35 U.S.C. §120 to the following U.S.        Utility Patent Applications: as a continuation in part to        Utility application Ser. No. 10/779,245, entitled “High Data        Throughput Wireless Local Area Network Receiver,” filed Feb. 13,        2004, now U.S. Pat. No. 7,539,501; as a continuation in part to        U.S. Utility application Ser. No. 10/778,751, entitled “Frame        Format for High Data Throughput Wireless Local Area Network        Transmissions,” filed Feb. 13, 2004, now U.S. Pat. No.        7,269,430; and as a continuation in part to U.S. Utility        application Ser. No. 10/778,754, entitled “Configurable Spectral        Mask for Use in a High Data Throughput Wireless Communication,”        filed Feb. 13, 2004, now U.S. Pat. No. 7,162,204.

BACKGROUND OF THE INVENTION

1. Technical Field of the Invention

This invention relates generally to wireless communication systems andmore particularly to supporting multiple wireless communicationprotocols within a wireless local area network.

2. Description of Related Art

Communication systems are known to support wireless and wire linedcommunications between wireless and/or wire lined communication devices.Such communication systems range from national and/or internationalcellular telephone systems to the Internet to point-to-point in-homewireless networks. Each type of communication system is constructed, andhence operates, in accordance with one or more communication standards.For instance, wireless communication systems may operate in accordancewith one or more standards including, but not limited to, IEEE 802.11,Bluetooth, advanced mobile phone services (AMPS), digital AMPS, globalsystem for mobile communications (GSM), code division multiple access(CDMA), local multi-point distribution systems (LMDS),multi-channel-multi-point distribution systems (MMDS), and/or variationsthereof.

Depending on the type of wireless communication system, a wirelesscommunication device, such as a cellular telephone, two-way radio,personal digital assistant (PDA), personal computer (PC), laptopcomputer, home entertainment equipment, et cetera communicates directlyor indirectly with other wireless communication devices. For directcommunications (also known as point-to-point communications), theparticipating wireless communication devices tune their receivers andtransmitters to the same channel or channels (e.g., one of the pluralityof radio frequency (RF) carriers of the wireless communication system)and communicate over that channel(s). For indirect wirelesscommunications, each wireless communication device communicates directlywith an associated base station (e.g., for cellular services) and/or anassociated access point (e.g., for an in-home or in-building wirelessnetwork) via an assigned channel. To complete a communication connectionbetween the wireless communication devices, the associated base stationsand/or associated access points communicate with each other directly,via a system controller, via the public switch telephone network, viathe Internet, and/or via some other wide area network.

For each wireless communication device to participate in wirelesscommunications, it includes a built-in radio transceiver (i.e., receiverand transmitter) or is coupled to an associated radio transceiver (e.g.,a station for in-home and/or in-building wireless communicationnetworks, RF modem, etc.). As is known, the transmitter includes a datamodulation stage, one or more intermediate frequency stages, and a poweramplifier. The data modulation stage converts raw data into basebandsignals in accordance with a particular wireless communication standard.The one or more intermediate frequency stages mix the baseband signalswith one or more local oscillations to produce RF signals. The poweramplifier amplifies the RF signals prior to transmission via an antenna.

As is also known, the receiver is coupled to the antenna and includes alow noise amplifier, one or more intermediate frequency stages, afiltering stage, and a data recovery stage. The low noise amplifierreceives inbound RF signals via the antenna and amplifies then. The oneor more intermediate frequency stages mix the amplified RF signals withone or more local oscillations to convert the amplified RF signal intobaseband signals or intermediate frequency (IF) signals. The filteringstage filters the baseband signals or the IF signals to attenuateunwanted out of band signals to produce filtered signals. The datarecovery stage recovers raw data from the filtered signals in accordancewith the particular wireless communication standard.

As is further known, the standard to which a wireless communicationdevice is compliant within a wireless communication system may vary. Forinstance, as the IEEE 802.11 specification has evolved from IEEE 802.11to IEEE 802.11b to IEEE 802.11a and to IEEE 802.11g, wirelesscommunication devices that are compliant with IEEE 802.11b may exist inthe same wireless local area network (WLAN) as IEEE 802.11g compliantwireless communication devices. As another example, IEEE 802.11acompliant wireless communication devices may reside in the same WLAN asIEEE 802.11g compliant wireless communication devices. When legacydevices (i.e., those compliant with an earlier version of a standard)reside in the same WLAN as devices compliant with later versions of thestandard, a mechanism is employed to insure that legacy devices knowwhen the newer version devices are utilizing the wireless channel as toavoid a collision.

For instance, backward compatibility with legacy devices has beenenabled exclusively at either the physical (PHY) layer (in the case ofIEEE 802.11b) or the Media-Specific Access Control (MAC) layer (in thecase of 802.11g). At the PHY layer, backward compatibility is achievedby re-using the PHY preamble from a previous standard. In this instance,legacy devices will decode the preamble portion of all signals, whichprovides sufficient information for determining that the wirelesschannel is in use for a specific period of time, thereby avoidcollisions even though the legacy devices cannot fully demodulate and/ordecode the transmitted frame(s).

At the MAC layer, backward compatibility with legacy devices is enabledby forcing devices that are compliant with a newer version of thestandard to transmit special frames using modes or data rates that areemployed by legacy devices. For example, the newer devices may transmitClear to Send/Ready to Send (CTS/RTS) exchange frames and/or CTS to selfframes as are employed in IEEE 802.11g. These special frames containinformation that sets the NAV (network allocation vector) of legacydevices such that these devices know when the wireless channel is in useby newer stations.

As future standards are developed (e.g., IEEE 802.11n and others), itmay be desirable to do more than just avoid collisions between newerversion devices and legacy devices. For instance, it may be desirable toallow newer version devices to communication with older version devices.

Therefore, a need exists for a method and apparatus that enablescommunication between devices of multiple protocols within a wirelesscommunication system, including wireless local area networks.

BRIEF SUMMARY OF THE INVENTION

The transmission of wide bandwidth signals in a network having legacydevices of the present invention substantially meets these needs andothers. In one embodiment a method for transmitting wide bandwidthsignals in a network that includes legacy devices begins by determiningchannel bandwidth of a channel that supports the wide bandwidth signalsin the network. The method continues by determining overlap of legacychannel bandwidth with the channel bandwidth of the channel. The methodcontinues by providing a legacy readable preamble section within thechannel where the legacy channel bandwidth overlaps the channelbandwidth of the channel.

In another embodiment, a method for generating a preamble of a frame fora wide-bandwidth channel wireless communication begins by generating alegacy carrier detect field. The method continues by generating achannel sounding field, wherein the channel sounding field includes aplurality of tones within the wide-bandwidth channel, wherein a firstset of the plurality of tones corresponds to tones of a legacy channelsounding field. The method continues by generating a legacy signalfield, wherein, in time, the legacy signal field follows the channelsounding field, which follows the legacy carrier detect field.

BRIEF DESCRIPTION OF THE SEVERAL VIEWS OF THE DRAWINGS

FIG. 1 is a schematic block diagram of a wireless communication systemin accordance with the present invention;

FIG. 2 is a schematic block diagram of a wireless communication devicein accordance with the present invention;

FIG. 3 is a schematic block diagram of another wireless communicationdevice in accordance with the present invention;

FIG. 4 is a diagram of a configurable spectral mask in accordance withthe present invention;

FIG. 5 is a diagram of example spectral masks in accordance with thepresent invention;

FIG. 6 is a diagram of a wide bandwidth channel with respect to legacychannels in accordance with the present invention;

FIG. 7 is a schematic block diagram of a wide bandwidth communication inaccordance with the present invention;

FIG. 8 is a schematic block diagram of another wide bandwidthcommunication in accordance with the present invention;

FIG. 9 is a schematic block diagram of yet another wide bandwidthcommunication in accordance with the present invention;

FIG. 10 is a diagram of wide bandwidth signal transmissions inaccordance with the present invention;

FIG. 11 is a diagram of other wide bandwidth signal transmissions inaccordance with the present invention;

FIG. 12 is a frequency diagram of sub-carriers of a wide bandwidthsignal in accordance with the present invention;

FIG. 13 is a logic diagram of a method for wireless communication inaccordance with the present invention; and

FIG. 14 is a logic diagram of another method for wireless communicationin accordance with the present invention.

DETAILED DESCRIPTION OF THE INVENTION

FIG. 1 is a schematic block diagram illustrating a communication system10 that includes a plurality of base stations and/or access points 12and 16, a plurality of wireless communication devices 18-32 and anetwork hardware component 34. The wireless communication devices 18-32may be laptop host computers 18 and 26, personal digital assistant hosts20 and 30, personal computer hosts 24 and 32 and/or cellular telephonehosts 22 and 28. The details of at least some of the wirelesscommunication devices will be described in greater detail with referenceto FIGS. 2 and/or 3.

The base stations or access points 12-16 are operably coupled to thenetwork hardware 34 via local area network connections 36, 38 and 40.The network hardware 34, which may be a router, switch, bridge, modem,system controller, et cetera provides a wide area network connection 42for the communication system 10. Each of the base stations or accesspoints 12 and 16 has an associated antenna or antenna array tocommunicate with the wireless communication devices in its regionalarea, which is generally referred to as a basic service set (BSS) 11,13. Typically, the wireless communication devices register with aparticular base station or access point 12 or 16 to receive servicesfrom the communication system 10.

Typically, base stations are used for cellular telephone systems andlike-type systems, while access points are used for in-home orin-building wireless networks. Regardless of the particular type ofcommunication system, each wireless communication device includes abuilt-in radio and/or is coupled to a radio. The radio includes a highlylinear amplifier and/or programmable multi-stage amplifier as disclosedherein to enhance performance, reduce costs, reduce size, and/or enhancebroadband applications.

Wireless communication devices 22, 23, and 24 are located in an area ofthe wireless communication system 10 where they are not affiliated withan access point. In this region, which is generally referred to as anindependent basic service set (IBSS) 15, the wireless communicationdevices communicate directly (i.e., point-to-point or point-to-multiplepoint), via an allocated channel to produce an ad-hoc network.

FIG. 2 is a schematic block diagram illustrating a wirelesscommunication device that includes the host device 18-32 and anassociated radio, or station, 60. For cellular telephone hosts, theradio 60 is a built-in component. For personal digital assistants hosts,laptop hosts, and/or personal computer hosts, the radio 60 may bebuilt-in or an externally coupled component. In this embodiment, thestation may be compliant with one of a plurality of wireless local areanetwork (WLAN) protocols including, but not limited to, IEEE 802.11n.

As illustrated, the host device 18-32 includes a processing module 50,memory 52, radio interface 54, input interface 58 and output interface56. The processing module 50 and memory 52 execute the correspondinginstructions that are typically done by the host device. For example,for a cellular telephone host device, the processing module 50 performsthe corresponding communication functions in accordance with aparticular cellular telephone standard.

The radio interface 54 allows data to be received from and sent to theradio 60. For data received from the radio 60 (e.g., inbound data), theradio interface 54 provides the data to the processing module 50 forfurther processing and/or routing to the output interface 56. The outputinterface 56 provides connectivity to an output display device such as adisplay, monitor, speakers, et cetera such that the received data may bedisplayed. The radio interface 54 also provides data from the processingmodule 50 to the radio 60. The processing module 50 may receive theoutbound data from an input device such as a keyboard, keypad,microphone, et cetera via the input interface 58 or generate the dataitself. For data received via the input interface 58, the processingmodule 50 may perform a corresponding host function on the data and/orroute it to the radio 60 via the radio interface 54.

Radio, or station, 60 includes a host interface 62, a basebandprocessing module 64, memory 66, a plurality of radio frequency (RF)transmitters 68-72, a transmit/receive (T/R) module 74, a plurality ofantennas 82-86, a plurality of RF receivers 76-80, and a localoscillation module 100. The baseband processing module 64, incombination with operational instructions stored in memory 66, executedigital receiver functions and digital transmitter functions,respectively. The digital receiver functions include, but are notlimited to, digital intermediate frequency to baseband conversion,demodulation, constellation demapping, decoding, de-interleaving, fastFourier transform, cyclic prefix removal, space and time decoding,and/or descrambling. The digital transmitter functions include, but arenot limited to, scrambling, encoding, interleaving, constellationmapping, modulation, inverse fast Fourier transform, cyclic prefixaddition, space and time encoding, and/or digital baseband to IFconversion. The baseband processing modules 64 may be implemented usingone or more processing devices. Such a processing device may be amicroprocessor, micro-controller, digital signal processor,microcomputer, central processing unit, field programmable gate array,programmable logic device, state machine, logic circuitry, analogcircuitry, digital circuitry, and/or any device that manipulates signals(analog and/or digital) based on operational instructions. The memory 66may be a single memory device or a plurality of memory devices. Such amemory device may be a read-only memory, random access memory, volatilememory, non-volatile memory, static memory, dynamic memory, flashmemory, and/or any device that stores digital information. Note thatwhen the processing module 64 implements one or more of its functionsvia a state machine, analog circuitry, digital circuitry, and/or logiccircuitry, the memory storing the corresponding operational instructionsis embedded with the circuitry comprising the state machine, analogcircuitry, digital circuitry, and/or logic circuitry.

In operation, the radio 60 receives outbound data 88 from the hostdevice via the host interface 62. The baseband processing module 64receives the outbound data 88 and, based on a mode selection signal 102,produces one or more outbound symbol streams 90. The mode selectionsignal 102 will indicate a particular mode as are illustrated in themode selection tables, which appear at the end of the detaileddiscussion. For example, the mode selection signal 102 may indicate afrequency band of 2.4 GHz, a channel bandwidth of 20 or 22 MHz and amaximum bit rate of 54 megabits-per-second. In this general category,the mode selection signal will further indicate a particular rateranging from 1 megabit-per-second to 54 megabits-per-second. Inaddition, the mode selection signal will indicate a particular type ofmodulation, which includes, but is not limited to, Barker CodeModulation, BPSK, QPSK, CCK, 16 QAM and/or 64 QAM.

The baseband processing module 64, based on the mode selection signal102 produces the one or more outbound symbol streams 90 from the outputdata 88. For example, if the mode selection signal 102 indicates that asingle transmit antenna is being utilized for the particular mode thathas been selected, the baseband processing module 64 will produce asingle outbound symbol stream 90. Alternatively, if the mode selectsignal indicates 2, 3 or 4 antennas, the baseband processing module 64will produce 2, 3 or 4 outbound symbol streams 90 corresponding to thenumber of antennas from the output data 88.

Depending on the number of outbound streams 90 produced by the basebandmodule 64, a corresponding number of the RF transmitters 68-72 will beenabled to convert the outbound symbol streams 90 into outbound RFsignals 92. The transmit/receive module 74 receives the outbound RFsignals 92 and provides each outbound RF signal to a correspondingantenna 82-86.

When the radio 60 is in the receive mode, the transmit/receive module 74receives one or more inbound RF signals via the antennas 82-86. The T/Rmodule 74 provides the inbound RF signals 94 to one or more RF receivers76-80. The RF receiver 76-80, which will be described in greater detailwith reference to FIG. 4, converts the inbound RF signals 94 into acorresponding number of inbound symbol streams 96. The number of inboundsymbol streams 96 will correspond to the particular mode in which thedata was received. The baseband processing module 60 receives theinbound symbol streams 90 and converts them into inbound data 98, whichis provided to the host device 18-32 via the host interface 62. For afurther discussion of an implementation of the radio, or station, 60refer to co-pending patent application entitled WLAN TRANSMITTER HAVINGHIGH DATA THROUGHPUT, having a provisional Ser. No. 60/545,854, and aprovisional filing date of Feb. 19, 2004 and co-pending patentapplication entitled WLAN RECEIVER HAVING AN ITERATIVE DECODER, having aprovisional Ser. No. 60/546,051 and a provisional filing date of Feb.19, 2004.

As one of average skill in the art will appreciate, the wirelesscommunication device of FIG. 2 may be implemented using one or moreintegrated circuits. For example, the host device may be implemented onone integrated circuit, the baseband processing module 64 and memory 66may be implemented on a second integrated circuit, and the remainingcomponents of the radio 60, less the antennas 82-86, may be implementedon a third integrated circuit. As an alternate example, the radio 60 maybe implemented on a single integrated circuit. As yet another example,the processing module 50 of the host device and the baseband processingmodule 64 may be a common processing device implemented on a singleintegrated circuit. Further, the memory 52 and memory 66 may beimplemented on a single integrated circuit and/or on the same integratedcircuit as the common processing modules of processing module 50 and thebaseband processing module 64.

FIG. 3 is a schematic block diagram illustrating a wirelesscommunication device that includes the host device 18-32 and anassociated radio 61. For cellular telephone hosts, the radio 61 is abuilt-in component. For personal digital assistants hosts, laptop hosts,and/or personal computer hosts, the radio 61 may be built-in or anexternally coupled component. The host device 18-32 operates asdiscussed above with reference to FIG. 2.

Radio 61 includes a host interface 62, baseband processing module 64, ananalog-to-digital converter 111, a filter module 109, an IF mixing downconversion stage 107, a receiver filter 101, a low noise amplifier 103,a transmitter/receiver switch 73, a local oscillation module 74, memory66, a digital transmitter processing module 76, a digital-to-analogconverter 78, a filter module 79, an IF mixing up conversion stage 81, apower amplifier 83, a transmitter filter module 85, and an antenna 86.The antenna 86 may be a single antenna that is shared by the transmitand receive paths as regulated by the Tx/Rx switch 73, or may includeseparate antennas for the transmit path and receive path. The antennaimplementation will depend on the particular standard to which thewireless communication device is compliant. The baseband processingmodule 64 functions as described above and performs one or more of thefunctions illustrated in FIGS. 5-19.

In operation, the radio 61 receives outbound data 88 from the hostdevice via the host interface 62. The host interface 62 routes theoutbound data 88 to the baseband processing module 64, which processesthe outbound data 88 in accordance with a particular wirelesscommunication standard (e.g., IEEE 802.11 Bluetooth, et cetera) toproduce outbound time domain baseband (BB) signals.

The digital-to-analog converter 77 converts the outbound time domainbaseband signals from the digital domain to the analog domain. Thefiltering module 79 filters the analog signals prior to providing themto the IF up-conversion module 81. The IF up conversion module 81converts the analog baseband or low IF signals into RF signals based ona transmitter local oscillation 83 provided by local oscillation module100. The power amplifier 83 amplifies the RF signals to produce outboundRF signals 92, which are filtered by the transmitter filter module 85.The antenna 86 transmits the outbound RF signals 92 to a targeted devicesuch as a base station, an access point and/or another wirelesscommunication device.

The radio 61 also receives inbound RF signals 94 via the antenna 86,which were transmitted by a base station, an access point, or anotherwireless communication device. The antenna 86 provides the inbound RFsignals 94 to the receiver filter module 101 via the Tx/Rx switch 73.The Rx filter 71 bandpass filters the inbound RF signals 94 and providesthe filtered RF signals to the low noise amplifier 103, which amplifiesthe RF signals 94 to produce amplified inbound RF signals. The low noiseamplifier 72 provides the amplified inbound RF signals to the IF downconversion module 107, which directly converts the amplified inbound RFsignals into inbound low IF signals or baseband signals based on areceiver local oscillation 81 provided by local oscillation module 100.The down conversion module 70 provides the inbound low IF signal orbaseband signal to the filtering/gain module 68. The filtering module109 filters the inbound low IF signals or the inbound baseband signalsto produce filtered inbound signals.

The analog-to-digital converter 111 converts the filtered inboundsignals into inbound time domain baseband signals. The basebandprocessing module 64 decodes, descrambles, demaps, and/or demodulatesthe inbound time domain baseband signals to recapture inbound data 98 inaccordance with the particular wireless communication standard beingimplemented by radio 61. The host interface 62 provides the recapturedinbound data 92 to the host device 18-32 via the radio interface 54.

As one of average skill in the art will appreciate, the wirelesscommunication device of FIG. 3 may be implemented using one or moreintegrated circuits. For example, the host device may be implemented onone integrated circuit, the baseband processing module 64 and memory 66may be implemented on a second integrated circuit, and the remainingcomponents of the radio 61, less the antenna 86, may be implemented on athird integrated circuit. As an alternate example, the radio 61 may beimplemented on a single integrated circuit. As yet another example, theprocessing module 50 of the host device and the baseband processingmodule 64 may be a common processing device implemented on a singleintegrated circuit. Further, the memory 52 and memory 66 may beimplemented on a single integrated circuit and/or on the same integratedcircuit as the common processing modules of processing module 50 and thebaseband processing module 64.

In the communication system of FIG. 1, the communication device may benewer devices as described with references to FIGS. 2 and 3 or may belegacy devices (e.g., compliant with an earlier version or predecessorof IEEE 802.11n standard). For the newer devices, they may configure thechannel bandwidth in numerous ways as illustrated in FIGS. 4 and 5.

FIG. 4 is a diagram of a configurable spectral mask 130 that includes achannel pass region 112, a transition region 114, and a floor region116. The transition region 114 includes a first attenuation region 118,a second attenuation region 120, and a third attenuation region 122.Such a spectral mask 130 promotes interoperability, coexistence, andsystem capacity by limiting interference to adjacent and other channelsfor a wide variety of applications and/or standards. The out of bandmask (e.g., the transition region 114 and the floor region 116) places alower bound on interference levels that can be expected in receiversregardless of their particular implementation. In an effort to minimizethe interference energy that appears on top of the desired signal, theout of band regions are made as small as possible.

To facilitate the above objective, the channel pass region 112, whichencompasses the desired signal, is of a value as close to the channelbandwidth as feasible. The transition region 114, which bounds theadjacent channel interference and is limited by the bandwidth of thebaseband processing module 64 of FIG. 3 and the intermediate frequencymixing stage of the up-conversion module 81, is selected to minimizesuch interference (i.e., post IF inter-modulation distortion (IMD)). Thefloor region 116, which bounds other channel interference, which isoutside the range of the filters and IMD limits and is generally limitedby the local oscillation 100 phase noise, is selected based onachievable phase noise levels.

For instance, the transition region 114 should have a roll off based onthe shoulder height of IMD, which may be assumed to be produced by a3^(rd) order compressive non-linearity. Based on this assumption, thedistorted transmit signal y(t) as a function of the ideal transmitsignal x(t) can be expressed as: y(t)=x(t)−f(Ax³(t)), where f( ) is abandpass filter that removes any DC or harmonic signals produced by thenon-linearity and A=4/3(1/OIP₃)², where OIP represents “Output 3^(rd)order intercept point”, and in the frequency domainY(f)=X(f)−AX(F)*X(f)*X(f). As such, the distorted signal bandwidth willbe no greater than three times the ideal signal bandwidth.

The floor region 116, which is limited by the local oscillator phasenoise, may be based on L(f) convolved with the power spectral density ofthe ideal transmit signal, where L(f) is defined in IEEE std. 1139-1999as the normalized phase noise spectral density and where y(t)=x(t) l(t)and Y(f)=X(f)*L(f), where x(t) represents the ideal RF signal, l(t) is amodel of the phase nose generated in the local oscillator, y(t)represents the resulting signal, and Y(f) is the resulting signal in thefrequency domain. Note that at 10 MHz or more from the carrier, phasenoise spectrum is relatively flat. From this, a −123 dBc/Hz noise floormay be achieved for 20 MHz channels and a −126 dBc/Hz noise floor may beachieved for 40 MHz channels.

FIG. 5 is a table illustrating a few examples of values for aconfigurable spectral mask 100. While the table includes channel widthsof 10, 20, and 40 MHz, one of average skill in the art will appreciate;other channel widths may be used. Further, the transition region mayinclude more or less attenuation regions than the three shown in FIG. 4.

FIG. 6 is a diagram of a wide bandwidth channel 130 (e.g., 40 MHz) withreference to two legacy channels 132, 134 (e.g., 20 MHz channel N and 20MHz channel N+1) and a legacy guard interval 136. To construct a widebandwidth signal 130 without regard as to whether legacy devices arepresent, the overlapping legacy portions of the two channels 132, 134are considered when establishing the format for the wide bandwidthchannel 130. In one embodiment, the preamble of the wide bandwidthsignal 130 includes a legacy header portion (e.g., a preamble inaccordance with an earlier version or predecessor of IEEE 802.11n)within the header spectral portion of the first channel 132 (e.g.,Channel N) and/or in the second channel 134 (e.g., Channel N+1). Assuch, legacy devices will be able to recognize the frame and, based onthe information contained within the preamble, refrain from transmissionuntil the wide bandwidth signal 130 has been transmitted.

For newer communication devices (i.e., those capable of transceiving thewide bandwidth signals), they transmit data and/or header informationwithin the guard band 136 of legacy channels and in the channels. Thisexpands the amount of data that may be transmitted within frame.

In one embodiment, the preamble and packet header of the wide-bandwidthsignal 130 uses the same spectrum that the payload of the wide-bandwidthsignal 130 will use to provide a legitimate preamble and packet headersthat can be transmitted in the portion of the spectrum used by legacydevices. Further, energy of the signal is transmitted in the legacyguard bands 136 so that the receiver may perform reliable preambleprocessing (carrier detection, gain control, channel estimation, etc.)on the wide-bandwidth signal 130.

In an embodiment, the multiple-channel legacy preambles and packetheaders will allow legacy-station reception of the preamble and reliablecarrier detection, gain control, and channel estimation over the legacychannels 132, 134. The guard-band 136 transmission allows for reliablecarrier detection, gain control, and channel estimation for theremainder of the spectrum (which will be used for transmission of thewide-bandwidth payload). Further, legacy stations are generally tolerantof adjacent channel transmissions which are at the same power as thedesired signal. Still further, legacy stations will see legitimatepreambles and packet headers so that they will be able to detect that asignal is present, perform gain control, channel estimation, and otherpreamble processing, and/or decode the packet header and thereby defertransmission until the end of the wide-band transmission. Yet further,the energy transmitted in the guard band 136 will be disregarded by thereceiver and will therefore not hinder the reception of the legacycomponents of the wide-band signal.

For the newer devices (e.g., IEEE 802.11n compliant), the devices willhave more energy for carrier detection, be able to perform a betterestimate of received power, thereby being able to do better gain controlon the packet, be able to estimate the channel response in the guardband (for use during payload demodulation), and have full access to themedium since legacy stations can see the transmission and defer untilits end.

FIG. 7 is a diagram depicting a wireless communication between twowireless communication devices 100 and 102 that are in a proximal regionwhere the only protocol that is used is IEEE 802.11n. The wirelesscommunication may be direct (i.e., from wireless communication device towireless communication device), or indirect (i.e., from a wirelesscommunication device to an access point to a wireless communicationdevice). In this example, wireless communication device 100 is providingframe 104 to wireless communication device 102. The frame 104 includes awireless communication set-up information field 106 and a data portion108. The wireless communication set-up information portion 106 includesa short training sequence 157 that may be 8 microseconds long, a 1^(st)supplemental long training sequence 159 that may be 4 microseconds long,which is one of a plurality of supplemental long training sequences 161,and a signal field 163 that may be 4 microseconds long. Note that thenumber of supplemental long training sequences 159, 161 will correspondto the number of transmit antennas being utilized for multiple inputmultiple output radio communications.

The data portion of the frame 104 includes a plurality of data symbols165, 167, 169 each being 4 microseconds in duration. The last datasymbol 169 also includes a tail bits and padding bits as needed.

FIG. 8 is a diagram of a wireless communication between two wirelesscommunication devices 100 and 102, each of which is compliant with IEEE802.11n. Such a communication is taking place within a proximal areathat includes 802.11n compliant devices, 802.11a compliant devicesand/or 802.11g compliant devices. In this instance, the wirelesscommunication may be direct or indirect where a frame 110 includes alegacy portion of the set-up information 112, remaining set-upinformation portion 114, and the data portion 108.

The legacy portion of the set-up information 112 includes a shorttraining sequence 157, which is 8 microseconds in duration, a longtraining sequence 171, which is 8 microseconds in duration, and a signalfield 173, which is 4 microseconds in duration. The signal field 173, asis known, includes several bits to indicate the duration of the frame110. As such, the IEEE 802.11a compliant devices within the proximalarea and the 802.11g compliant devices within the proximal area willrecognize that a frame is being transmitted even though such deviceswill not be able to interpret the remaining portion of the frame. Inthis instance, the legacy devices (IEEE 802.11a and IEEE 802.11g) willavoid a collision with the IEEE 802.11n communication based on a properinterpretation of the legacy portion of the set-up information 112.

The remaining set-up information 114 includes additional supplementallong training sequences 159, 161, which are each 4 microseconds induration. The remaining set-up information further includes a high datasignal field 163, which is 4 microseconds in duration to provideadditional information regarding the frame. The data portion 108includes the data symbols 165, 167, 169, which are 4 microseconds induration as previously described with reference to FIG. 7. In thisinstance, the legacy protection is provided at the physical layer.

$S_{k} = {\begin{bmatrix}s_{10,k} & s_{11,k} & s_{12,k} \\s_{20,k} & s_{21,k} & s_{22,k} \\s_{30,k} & s_{31,k} & s_{32,k}\end{bmatrix} = \begin{bmatrix}s_{00,k} & {s_{00,k} \cdot {\mathbb{e}}^{{\mathbb{i}} \cdot \theta_{k}}} & {s_{00,k} \cdot {\mathbb{e}}^{{\mathbb{i}} \cdot \phi_{k}}} \\s_{00,k} & {s_{00,k} \cdot {\mathbb{e}}^{{\mathbb{i}} \cdot {({\theta_{k} - \frac{4 \cdot \pi}{3}})}}} & {s_{00,k} \cdot {\mathbb{e}}^{{\mathbb{i}} \cdot {({\theta_{k} - \frac{2 \cdot \pi}{3}})}}} \\s_{00,k} & {s_{00,k} \cdot {\mathbb{e}}^{{\mathbb{i}} \cdot {({\theta_{k} - \frac{2 \cdot \pi}{3}})}}} & {s_{00,k} \cdot {\mathbb{e}}^{{\mathbb{i}} \cdot {({\theta_{k} - \frac{4 \cdot \pi}{3}})}}}\end{bmatrix}}$ θ_(k) = π ⋅ k/(4 ⋅ N_(subcarriers))ϕ_(k) = π ⋅ (k + 4)/(2 ⋅ N_(subcarriers))

FIG. 9 is a diagram of a wireless communication between two wirelesscommunication devices 100 and 102 that are both IEEE 802.11n compliant.The wireless communication may be direct or indirect within a proximalarea that includes IEEE 802.11 compliant devices, IEEE 802.11a, 802.11band/or 802.11g devices. In this instance, the frame 111 includes alegacy portion of the set-up information 112, remaining set-upinformation 114 and the data portion 108. As shown, the legacy portionof the set-up information 112, or legacy frame, includes an IEEE 802.11PHY preamble (i.e., STS 157, LTS 171, and signal field 173) and a MACpartitioning frame portion 175, which indicates the particulars of thisparticular frame that may be interpreted by legacy devices. In thisinstance, the legacy protection is provided at the MAC layer.

The remaining set-up information 114 includes a plurality ofsupplemental long training sequences 159, 161 and the high data signalfield 163. The data portion 108 includes a plurality of data symbols165, 167, 169 as previously described.

FIG. 10 is a diagram of a wide bandwidth signal transmission. In thisembodiment, two legacy channels 132, 134 (channel N and channel N+1) anda guard band 136 are aggregated together to produce a composite widebandwidth signal 130-1 for a single input single output transmission. Asone of average skill in the art will appreciate, three or more legacychannels with multiple guard bands may be combined in a similar mannerto produce a wider bandwidth composite signal.

FIG. 11 is a diagram of a wide bandwidth signal 130-2 multiple inputmultiple output transmission. In this embodiment, two legacy channels132, 134 (channel N and channel N+1) and a guard band 136 aresimultaneously transmitted on a channel and are combined via thetransmission medium. As one of average skill in the art will appreciate,three or more legacy channels with multiple guard bands may be combinedin a similar manner to produce a wider bandwidth composite signal.

FIG. 12 is a diagram of the wide bandwidth channel 130 of FIGS. 10 and11 in the frequency domain. In this illustration, the subcarriers ofchannel N 132, the guard band 136, and channel N+1 134 comprise the widebandwidth channel 130.

FIG. 13 is a logic diagram of a method for transmitting wide bandwidthsignals in a network that includes legacy devices that begins at step140 where an RF transmitter determines channel bandwidth of a channelthat supports the wide bandwidth signals in the network. The method thenproceeds to step 142 where the RF transmitter determines overlap oflegacy channel bandwidth with the channel bandwidth of the channel. Themethod then continues to step 144 where the RF transmitter provides alegacy readable preamble section within the channel where the legacychannel bandwidth overlaps the channel bandwidth of the channel.

The method of FIG. 13 may further includes utilizing at least a portionof payload spectrum of the channel that for packet header transmission,wherein the packet header transmission includes at least a portion ofthe legacy readable preamble. In such an embodiment, the utilization ofthe at least a portion of the payload spectrum may further includeutilizing a same power spectral density for the packet headertransmission and for the payload and/or utilizing a different powerspectral density for the packet header transmission and for the payload.

The method of FIG. 13 may further include, interpreting, by the legacydevices, the legacy readable preamble such that the legacy devicesappropriately defer transmissions and decode a portion of the widebandwidth signals within a channel spectrum of the legacy devices.

The method of FIG. 13 may further include generating a wide-bandwidthpreamble of the wide bandwidth signals for at least one of: carrierdetection, gain control, frequency offset estimation, channelestimation, transmission deference, and data demodulation.

FIG. 14 is a logic diagram of a method for generating a preamble of aframe for a wide-bandwidth channel wireless communication that begins atstep 150 where an RF transmitter generates a legacy carrier detectfield. The method then proceeds to step 152 where the RF transmittergenerates a channel sounding field, wherein the channel sounding fieldincludes a plurality of tones within the wide-bandwidth channel, whereina first set of the plurality of tones corresponds to tones of a legacychannel sounding field. The method then proceeds to step 154 where theRF transmitter generates a legacy signal field, wherein, in time, thelegacy signal field follows the channel sounding field, which followsthe legacy carrier detect field.

The method of FIG. 14 may further include the RF transmitter generatingat least one additional channel sounding field that includes a secondplurality of tones and generating another signal field, wherein the atleast one additional channel sounding field follows, in time, the legacysignal field, and the another signal field follows the at least oneadditional channel sounding field.

The method of FIG. 14 may further include the RF transmitter generatingthe legacy carrier detect field in accordance with a legacy wirelessprotocol, wherein a legacy channel of the legacy wireless protocol has afirst channel bandwidth and wherein the wide-bandwidth channel includesat least two legacy channels. Next, the RF transmitter generates a firstportion of the channel sounding field in accordance with the legacywireless protocol, wherein the first portion of the channel soundingfield corresponds to the first set of the plurality of tones. Next, theRF transmitter generates a second portion of the channel sounding fieldin accordance with a current wireless protocol, wherein the secondportion of the channel sounding field corresponds to remaining tones ofthe plurality of tones.

In accordance with the preceding paragraph, the method of FIG. 14 mayfurther include the RF transmitter generating a short training sequenceas the legacy carrier detect field in accordance with a legacy versionof an IEEE 802.11 protocol. Next, the RF transmitter generates a longtraining sequence as the first portion of the channel sounding field inaccordance with a legacy version of an IEEE 802.11 protocol. Next, theRF transmitter repeats the long training sequence as at least part ofthe second portion of the channel sounding field in accordance with acurrent version of an IEEE 802.11 protocol. The RF transmitter mayfurther generate the second portion of the channel sounding fieldfurther by generating tones within a guard band field between the atleast two legacy channels of the wide-bandwidth channel.

As one of average skill in the art will appreciate, the term“substantially” or “approximately”, as may be used herein, provides anindustry-accepted tolerance to its corresponding term. Such anindustry-accepted tolerance ranges from less than one percent to twentypercent and corresponds to, but is not limited to, component values,integrated circuit process variations, temperature variations, rise andfall times, and/or thermal noise. As one of average skill in the artwill further appreciate, the term “operably coupled”, as may be usedherein, includes direct coupling and indirect coupling via anothercomponent, element, circuit, or module where, for indirect coupling, theintervening component, element, circuit, or module does not modify theinformation of a signal but may adjust its current level, voltage level,and/or power level. As one of average skill in the art will alsoappreciate, inferred coupling (i.e., where one element is coupled toanother element by inference) includes direct and indirect couplingbetween two elements in the same manner as “operably coupled”. As one ofaverage skill in the art will further appreciate, the term “comparesfavorably”, as may be used herein, indicates that a comparison betweentwo or more elements, items, signals, etc., provides a desiredrelationship. For example, when the desired relationship is that signal1 has a greater magnitude than signal 2, a favorable comparison may beachieved when the magnitude of signal 1 is greater than that of signal 2or when the magnitude of signal 2 is less than that of signal 1.

The preceding discussion has presented various embodiments for widebandwidth communications in a network that includes legacy devices. Asone of average skill in the art will appreciate, other embodiments maybe derived from the teachings of the present invention without deviatingfrom the scope of the claims.

What is claimed is:
 1. A method for transmitting a wirelesscommunication, the method comprises: generating a first legacy frame inaccordance with a legacy version of the IEEE 802.11 protocol; generatinga second legacy frame in accordance with the legacy version of the IEEE802.11 protocol; transmitting the first legacy frame and the secondlegacy frame in a current channel having a wide channel bandwidth inaccordance with a current version of the IEEE 802.11 protocol; andwherein the first legacy frame and the second legacy frame are duplicateframes, wherein the first legacy frame includes a first legacy preambleportion having a first legacy short training sequence and a first legacylong training sequence and the second legacy frame includes a secondlegacy preamble portion having a second legacy short training sequenceand a second legacy long training sequence.
 2. The method of claim 1,wherein the current channel in accordance with a current version of theIEEE 802.11 protocol has an approximately 40 MHz wide channel bandwidth.3. The method of claim 2, wherein the first legacy frame is transmittedin a first 20 MHz channel bandwidth of the approximately 40 MHz widechannel bandwidth of the current channel and the second legacy frame istransmitted in a second 20 MHz channel bandwidth of the approximately 40MHz wide channel bandwidth of the current channel.
 4. The method ofclaim 3, further comprising: generating a guard band; and transmittingthe guard band between the first legacy frame and the second legacyframe in the approximately 40 MHz wide channel bandwidth of the currentchannel.
 5. The method of claim 1, wherein a legacy channel of thelegacy version of the IEEE 802.11 protocol has a channel bandwidth ofapproximately 20 MHz.
 6. The method of claim 5, wherein the first legacypreamble portion of the first legacy frame is a duplicate of the secondlegacy preamble portion of the second legacy frame.
 7. The method ofclaim 1, further comprising: aggregating the first legacy frame and thesecond legacy frame to generate a composite wideband signal; andtransmitting the composite wideband signal in the current channel havingthe wide channel bandwidth in accordance with the current version of theIEEE 802.11 protocol over a first antenna for a single input singleoutput (SISO) wireless communication.
 8. The method of claim 1, furthercomprising: transmitting the first legacy frame and the second legacyframe in the current channel having the wide channel bandwidth inaccordance with the current version of the IEEE 802.11 protocol over aplurality of antennas for a multiple input multiple output (MIMO)wireless communication.
 9. A wireless communication device, comprises: ahost device; and a wireless station operable to: generate a first legacyframe in accordance with a legacy version of the IEEE 802.11 protocol;generate a second legacy frame in accordance with the legacy version ofthe IEEE 802.11 protocol; transmit the first legacy frame and the secondlegacy frame in a current channel having a wide channel bandwidth inaccordance with a current version of the IEEE 802.11 protocol; andwherein the first legacy frame and the second legacy frame are duplicateframes including a legacy preamble portion having a legacy shorttraining sequence and a legacy long training sequence.
 10. The wirelesscommunication device of claim 9, wherein the current channel inaccordance with a current version of the IEEE 802.11 protocol has anapproximately 40 MHz wide channel bandwidth.
 11. The wirelesscommunication device of claim 10, wherein the first legacy frame istransmitted in a first 20 MHz channel bandwidth of the approximately 40MHz wide channel bandwidth of the current channel and the second legacyframe is transmitted in a second 20 MHz channel bandwidth of theapproximately 40 MHz wide channel bandwidth of the current channel. 12.The wireless communication device of claim 11, wherein the wirelessstation is further operable to: generate a guard band; and transmit theguard band between the first legacy frame and the second duplicatelegacy frame in the approximately 40 MHz wide channel bandwidth of thecurrent channel.
 13. The wireless communication device of claim 9,wherein a legacy channel of the legacy version of the IEEE 802.11protocol has a channel bandwidth of approximately 20 MHz.
 14. Thewireless communication device of claim 9, wherein the wireless stationis further operable to: aggregate the first legacy frame and theduplicate legacy frame to generate a composite wideband signal; andtransmit the composite wideband signal in the current channel having thewide channel bandwidth in accordance with the current version of theIEEE 802.11 protocol over a first antenna for a single input singleoutput (SISO) wireless communication.
 15. The wireless communicationdevice of claim 9, wherein the wireless station is further operable to:transmit the first legacy frame and the second legacy frame in thecurrent channel having the wide channel bandwidth in accordance with thecurrent version of the IEEE 802.11 protocol over a plurality of antennasfor a multiple input multiple output (MIMO) wireless communication. 16.A wireless communication device, comprises: a baseband processing moduleoperable to: generate a first frame with a legacy preamble in accordancewith a legacy version of the IEEE 802.11 protocol, wherein the legacypreamble portion includes a legacy short training sequence and a legacylong training sequence; and generate a duplicate frame with the legacypreamble in accordance with the legacy version of the IEEE 802.11protocol; and a transmitter section operable to: transmit the firstframe and the duplicate frame in a current channel having a wide channelbandwidth in accordance with a current version of the IEEE 802.11protocol.
 17. The wireless communication device of claim 16, wherein thecurrent channel in accordance with a current version of the IEEE 802.11protocol has an approximately 40 MHz wide channel bandwidth.
 18. Thewireless communication device of claim 17, wherein the transmittersection is operable to: transmit the first frame in a first 20 MHzchannel bandwidth of the approximately 40 MHz wide channel bandwidth ofthe current channel; and transmit the duplicate frame in a second 20 MHzchannel bandwidth of the approximately 40 MHz wide channel bandwidth ofthe current channel.
 19. The wireless communication device of claim 18,wherein a legacy channel of the legacy version of the IEEE 802.11protocol has a channel bandwidth of approximately 20 MHz.
 20. Thewireless communication device of claim 16, wherein the transmittersection is further operable to: transmit a guard band between the firstframe and the duplicate frame in the current channel having the widechannel bandwidth.